Michael Burton

2015

We continue monitoring (since 2003) of snapper grouper populations in the TER for a final two years. While we have observed recovery of spawning aggregations (SPAGs) of mutton snapper, knowledge of site fidelity of SPAGs is limited and continued data collection should elucidate if these recovery trends are stable. Extending this project will also allow us to increase the quality and quantity of mapping products with new high-resolution multibeam technology, improve our habitat classification and biomass estimates, and investigate a recently discovered cubera snapper aggregation. We will investigate the ability of large predators in marine reserves to act as natural controls for invasive lionfish. Despite potentially significant impacts to the invaded community (e.g., reduction of reef fish recruitment by 79%), no methods of control beyond local, physical removals have been investigated. In their native range lionfish are thought to have few natural predators, but no research supports this claim. In their invaded range, lionfish have been found in the stomachs of piscivorous groupers, but the potential role of predation in decreasing lionfish numbers remains unknown. Predation by large carnivores may represent the best control for lionfish, as low densities of lionfish occur in their native range on reefs with robust grouper populations. Reduced numbers of large predators in many invaded locations means that predation on lionfish may not occur at levels high enough to provide effective control. However, increased densities of exploited predators in marine reserves are often the first signs of positive responses to protection from fishing. If predation on lionfish is a controlling mechanism, reserves may act as refugia where community assemblages are maintained with low densities of invaders by healthy populations of large predators. Reserves should thus be one of the first places to search for evidence of lionfish population control by predators. This project component leverages 11 years of fish community data in the TSER, where we have seen densities of large predators (e.g., groupers, sharks) increase since reserve inception (2001-2002: 1.49 +/- 0.102 combined large snapper-grouper density per 30m transect vs 2009-2011: 5.83 +/- 2.46). The recent lionfish invasion (2010) in the TSER provides a unique opportunity to examine predation’s role in controlling lionfish densities. The TSER’s remote location, small area (10 sq. km minimizing habitat variability) and research-only designation means limited removals of both predators and lionfish, thus avoiding confounding analyses of relationships between the two. We will conduct surveys for three years (Years 1 and 2 complete) to track the predatory and prey fish community responses to lionfish. One analysis will compare lionfish densities across a gradient of predator densities within the TSER, and with data from the TNER where predator sizes and abundance are lower and removal of lionfish less regulated. Results have important implications for the effectiveness of marine reserves and for the management and natural control of lionfish. Partnerships include NOS CCFHR biologists, providing lionfish monitoring expertise; FKNMS, end users of research, informing management; and FWC, research partners with whom we leverage days-at-sea for conducting research.

This final year of biennial monitoring of reef fish populations in the TER will add two more years of data points to our long term data set. The additional data should provide more clarification on the persistence and stability of mutton snapper spawning aggregations. Continued evidence of spawning aggregation persistence, elevated numbers relative to earlier surveys, and further elaboration on the function and temporal extent of the cubera snapper spawning aggregation would increase the value of the TSER reserve designation, providing additional evidence for the utility of reserves as a management tool to protect sensitive marine resources.The project will provide another year of valuable data on the role of predator populations to act as a control on invasive lionfish populations, as well as examining the potential ecological impacts of lionfish to the native marine community, including cascading impacts to the benthos (coral, algae, sponge, etc.). Mumby et al. (2011) recently demonstrated a 7­fold reduction in lionfish biomass relative to grouper biomass in a Bahamian marine reserve. The TSER is another location where predator abundance is higher due to long­term total protection from fishing effort. We hypothesize that this may lead to increased predation on lionfish, allowing large predators to act as a natural control, a process that may not occur in other locations along the Florida reef tract due to the relative paucity of predators outside the TER. This study could provide evidence that healthy populations of native fishes are the best defense against ecosystem disruptions (invasive species), giving managers evidence that protection from overfishing can allow healthy coral reef ecosystems to persist.

• Florida

• N/A

Fishing

Closed

Completed

https://www.coris.noaa.gov/search/rest/find/document?searchText=projectNumber%3A453%20OR%20projectTitle%3A"Assessing%20reef%20fish%20population%20recovery%2C%20SPAGs%20and%20lionfish%20impacts%20on%20prey%20and%20predator%20communities%20in%20the%20TER."&start=1&max=10&f=searchPage